Spark-plug



UNITED sTATEs PATENT oEEioE.

.roma mi: mrc'r'rn, or cmcneo, rumors.

SPARK-rime.

To all whom it may' concern:

.Be itknown that I, JOSEPH REN AYoTTE, a subject of the King of Great Britain, residing at Chicago, in the county of Cook and State of -Illinois, have invented certain new jects of my invention will become'readily apparent to persons skilled in the art, from a consideration of the followin description when taken in conjunction wii the drawings, wherein Figure 1 is an elevation-of my improved spark plug.

Fig. 2 is a central vertical section thereof.

Fig. 3 is a transverse section taken on line 3 3 of Fig. 2. Y

Fig. 4 is a central vertical section of the porcelain core.

Fig. 5-is an end view of the plug looking at the bottom end.

In all the views the same reference characters are employed to indicate similar parts.

The usual metal shell of the plug 10 is screw threaded, as at 11, on its bottom end,

and is provided with a cylindrical opening 12 for the lower end of -the porcelain core 13 and with a larger opening 14 to accomrnodate the larger portion of the core.

- The lower portion of the core 13 is tapered, as at 15, and it is provided with a central bore 16 which lis enlarged near its top end, as at 17. l A central conductor`18 passes through the perforation 16 and terminates, as at 19, in one electrode for the lower spark gap. The upper end of the wire, or conductor 18, is transversely bent into serpentine or hump fashion, as at 20, to prevent its longitudinal movement when embedded in the surrounding cement 21,1 which is to be placed'withn the aperture 17, at the time of assembling the parts.

The upper end' of the conductor or wire, terminates in amore or less refractory terminal 22, which may be Welded thereto, and which may consist of a metal that is more refractory than the main'body part 18 of the 1 In placin Specification ot Letterslfatent. Patented Oct, 14, 1919,

Application led November 2'?, 1,918. Serial No. 264,294.

conductor. -If desired, a small portion of 'Irore durable material may also be welded to the lower end of the'conductor 18 to form tlieterminal 19, and by this means I am enabled to use a cheaper metal for the main body part of the central. conductor 18.

the core 13 in the shell 10 a gasket 23-is rst put into the opening 14 and then the core is placed inside of the shell and finally another asketl24 is placed inside of the opening, a ter which the flange 25 is pressed inwardly toward the axis of the shell, either by pressure or by spinning, so as' to hold the central ycore 13 firmly and permanently in place, within the shell.

, The core 1s provided on its upper end with an annular enlargement or shoulder 26 to which a metal cap 27 ,-is attached. The cap is provided with `a hollow part having a skirt 28 and having a centrally located, upwardly projecting, threaded stem 29,'for the binding nut 30. The cap is also provided with a yshoulder part 31 which lies within the shoulder 32 of the core, and which overlies a more or less resilient gasket or ring 33. v

The lower portion 34 of the skirt 28 is then spun or pressed inwardly, under the shoulvder 35 of the annular head 26, to hold the cap 27 in place. The resiliency of the washer, or ring 33, permits more or less' relative lateralmo'vement of the cap 27 and of the parts 29 and 30, which tend to move laterally relativeto the core on account of their dlstance from the point at whichv the plug, .as a whole,'is attached to the engine. The vibration of the cap and its parts 1s,

therefore,not imparted to the core, that 1`s l to say, the momentum and inertia of the cap is-not, on account of the resilient connection- 'between the core of such a character as to produce fracture of the core as a result of accumulatedl vibrations to which-it is subjected. Y

. A sparking point 37 may be inserted m the cap 28, at its axial center, to coperate with a sparking point 32 of the central conductor, or the point 37. may be welded to the inner .surface of the cap, if desired, or it may be a projecting part of the cap itself.

There is a space 38, between the upper end of the core and the in ner lower surface of the cap wall, within which the extra spark -gap is located. The object of this is to intensify the spark at the main spark gap between the electrodes 19 and 39. The confronting end 40, of the electrode 39, is

upturned but is not out-turned. In this Way the rounded surface of both of the electrodes 19 and 40 confront each other so that a more abrupt discharge of the spark across the gap is obtained, and as this occurs at the very end of the terminal, there is no part above the spark gap to be burned off, as when the part is formed into a complete yA. hole 41 is drilled through the cap to provide a vent for the space 38 within which the extra spark gap is provided.

Having described my invention, what I Claim is l. A spark plug having an insulating core, With an axially extending bore terminating at its upper end in an enlarged recess; a central conductor of uniform diameter lextending through the bore providing one electrode at its lower end and unattached to the core throughout the smaller bore, having a sinuously bent portion confined to the larger bore and embedded in applied cement Within the larger bore, said sinuous portion terminating near the upper end of the core, beyond the cement, and a cap secured and spaced away from said core to provide a spark gap.

2. A spark plug having an insulating core with anaxially extending bore terminating in an enlarged recess near its upper end; a central conductor extending through the bore providing one electrode for the main spark gap at its lower end, and havin its upper end sinuously bent, all of said ent portion embedded in cement in said recess and terminating in the axial plane of the body part of said conductor; a cap, carrying a binding screw and yieldingly secured to the upper end of the core and overlying the contorted upper end of the central conductor, out of contact therewith; a spark point of relatively refractory material secured to the upper end of the central conductor and a coperating similar spark point provided on the cap and out of contact with the first mentioned point to provide an auxiliary spark gap Within the cap.

In testimony whereof I hereunto subscribed my name.

JOSEPH REN AYOTTE. 

